Estranediols profiling in calves' urine after 17β-nandrolone laureate ester administration

17β-Nandrolone (17β-NT) is one of the most recurrent forbidden anabolic steroid used in meat producing animals breeding. Because efficient control must both take into account metabolic patterns and associated kinetics of elimination, the metabolism of 17β-NT in bovines has already been investigated and is well documented, but only focussing on its main metabolites (i.e. 17α-nandrolone, 19-noretiocholanolone and 19-norandrostenedione). The goal of the present study was to enlarge this panel of 17β-NT metabolites, especially through the urinary estranediols fraction in order to perform a more global steroid profiling upon 17β-nortestosterone laureate ester administration in calves. A GC-MS/MS method has been developed to monitor and quantify 5 estranediols isomers including 5α-estrane-3β,17β-diol (abb), 5β-estrane-3α,17β-diol (bab), 5α-estrane-3β,17α-diol (aba), 5α-estrane-3α,17β-diol (aab) and 5β-estrane-3α,17α-diol (baa). Their urinary elimination kinetics have been established allowing detection of 4 estranediols up to several days after administration. All animals demonstrated homogeneous patterns of elimination both from a qualitative (metabolite profile) and quantitative point of view (elimination kinetics in urine). 5α-Estrane-3β,17α-diol (aba) was found as the major metabolite with concentrations up to 100μgL^-1.